As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
One type of information handling system is a modular information handling systems such as a multi-blade servers. Multi-blade servers typically include midplanes for attaching multiple blades (sometimes referred to as “bricks”). Midplanes allow the multiple blades to be interconnected in a single chassis and to share a common power source. Each blade typically includes a processor and memory and may store data, process information, or perform particular tasks.
During the operation of a multi-blade server system, a user may need to replace or add a blade to the system. This may be necessary if a blade becomes corrupt or if the user desires to add another blade to the system. To add or remove a blade, a user may shut down the entire system to add the new blade or replace a damaged blade. This method is disadvantageous because a user must take the time to shut down the system and loses the functionality of the other blades while the system is shut down.
A second, and more preferable option for the user would be to “hot-plug” the blade into the server system. That is, to install a new blade while the system is running. Hot-plugging has the advantage that a user does not have to shut down the entire server and lose the functionality of the other blades. However, this option has disadvantages. In server systems, especially large ones able to hold ten or more blades, hot-plugging a blade may result in a large inrush current. This large inrush current may damage circuitry or components within the blade that has been hot plugged. The resulting stress and damage on the blade's circuitry and components may negatively affect performance of the blade and reduce the life of the blade.
The inrush current experienced when hot-plugging a blade is caused by the large power supply of the midplane and the large capacitors on the blade. A multi-blade server system with a large number of blades requires a relatively larger power supply. In order to effectively filter the noise of a larger power supply, blades utilize capacitors. Capacitors are able to effectively filter the noise of the larger power supply; however, large capacitors create hot-plugging problems. When the blade is hot-plugged in, the blade immediately absorbs a large inrush of current to fill its large capacitor. This large inrush of current may stress and damage the blade.
In order to reduce inrush current, previous solutions have focused on reducing the size of the blade's capacitors. Although this effectively reduces the inrush current on the blade, this also reduces the effectiveness of filtering noise because a smaller capacitor cannot buffer the fluctuation of electrical current as well as a larger capacitor.